I. Field
The present disclosure relates generally to communication, and more specifically to techniques for searching for wireless communication networks.
II. Background
Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.
A wireless network may include many Node Bs (or base stations) that can support communication for many user equipments (UEs), e.g., cellular phones. Upon power up or loss of coverage, a UE may perform a system search in order to find a suitable cell from which the UE can receive communication services. The term “cell” can refer to a Node B and/or its coverage area depending on the context in which the term is used. A “suitable cell” is a cell on which the UE may camp on to obtain full service. A cell may be deemed as suitable if it meets certain criteria. Full service may also be referred to as normal service and may include all communication services available to the UE based on its service subscription. If a suitable cell is found, then the UE may perform registration with the cell, if necessary. The UE may then “camp” on the suitable cell if the UE is in an idle mode and not actively communicating with the cell.
If a suitable cell is not found by the system search, then the UE may select any acceptable cell. An “acceptable cell” is a cell on which the UE may camp on to obtain limited service, which may include only emergency calls. A cell may be deemed as acceptable if it satisfies certain conditions. If the UE is camped on an acceptable cell, then it is desirable for the UE to periodically perform system searches to find a suitable cell from which the UE can receive full service.